/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.context.config;

import org.w3c.dom.Element;

import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.parsing.BeanComponentDefinition;
import org.springframework.beans.factory.support.AbstractBeanDefinition;
import org.springframework.beans.factory.support.BeanDefinitionBuilder;
import org.springframework.beans.factory.support.RootBeanDefinition;
import org.springframework.beans.factory.xml.AbstractSingleBeanDefinitionParser;
import org.springframework.beans.factory.xml.ParserContext;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.weaving.AspectJWeavingEnabler;
import org.springframework.lang.Nullable;
import org.springframework.util.ClassUtils;

/**
 * Parser for the &lt;context:load-time-weaver/&gt; element.
 *
 * @author Juergen Hoeller
 * @since 2.5
 */
class LoadTimeWeaverBeanDefinitionParser extends AbstractSingleBeanDefinitionParser {

    /**
     * The bean name of the internally managed AspectJ weaving enabler.
     *
     * @since 4.3.1
     */
    public static final String ASPECTJ_WEAVING_ENABLER_BEAN_NAME =
            "org.springframework.context.config.internalAspectJWeavingEnabler";

    private static final String ASPECTJ_WEAVING_ENABLER_CLASS_NAME =
            "org.springframework.context.weaving.AspectJWeavingEnabler";

    private static final String DEFAULT_LOAD_TIME_WEAVER_CLASS_NAME =
            "org.springframework.context.weaving.DefaultContextLoadTimeWeaver";

    private static final String WEAVER_CLASS_ATTRIBUTE = "weaver-class";

    private static final String ASPECTJ_WEAVING_ATTRIBUTE = "aspectj-weaving";


    @Override
    protected String getBeanClassName(Element element) {
        if (element.hasAttribute(WEAVER_CLASS_ATTRIBUTE)) {
            return element.getAttribute(WEAVER_CLASS_ATTRIBUTE);
        }
        return DEFAULT_LOAD_TIME_WEAVER_CLASS_NAME;
    }

    @Override
    protected String resolveId(Element element, AbstractBeanDefinition definition, ParserContext parserContext) {
        return ConfigurableApplicationContext.LOAD_TIME_WEAVER_BEAN_NAME;
    }

    @Override
    protected void doParse(Element element, ParserContext parserContext, BeanDefinitionBuilder builder) {
        builder.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);

        if (isAspectJWeavingEnabled(element.getAttribute(ASPECTJ_WEAVING_ATTRIBUTE), parserContext)) {
            if (!parserContext.getRegistry().containsBeanDefinition(ASPECTJ_WEAVING_ENABLER_BEAN_NAME)) {
                RootBeanDefinition def = new RootBeanDefinition(ASPECTJ_WEAVING_ENABLER_CLASS_NAME);
                parserContext.registerBeanComponent(
                        new BeanComponentDefinition(def, ASPECTJ_WEAVING_ENABLER_BEAN_NAME));
            }

            if (isBeanConfigurerAspectEnabled(parserContext.getReaderContext().getBeanClassLoader())) {
                new SpringConfiguredBeanDefinitionParser().parse(element, parserContext);
            }
        }
    }

    protected boolean isAspectJWeavingEnabled(String value, ParserContext parserContext) {
        if ("on".equals(value)) {
            return true;
        } else if ("off".equals(value)) {
            return false;
        } else {
            // Determine default...
            ClassLoader cl = parserContext.getReaderContext().getBeanClassLoader();
            return (cl != null && cl.getResource(AspectJWeavingEnabler.ASPECTJ_AOP_XML_RESOURCE) != null);
        }
    }

    protected boolean isBeanConfigurerAspectEnabled(@Nullable ClassLoader beanClassLoader) {
        return ClassUtils.isPresent(SpringConfiguredBeanDefinitionParser.BEAN_CONFIGURER_ASPECT_CLASS_NAME,
                beanClassLoader);
    }

}
